Nielsen is ready for the next phase of TV ratings, or so it says — but is the rest of the industry?

Despite what might seem like common wisdom, live TV consumption is actually unchanged in the past three years, Nielsen Executive Vice President of U.S. Media Cheryl Idell told journalists at Tuesday’s Summer Television Critics Association kick-off panel. Still, time-shifted viewing has seen a 30 percent increase, she added.

But now it’s time to accurately measure cross-platform ratings, including mobile viewing. And that’s not easy, Nielsen admits — but it’s coming this fall.

Here’s what Nielsen is doing to take it on: The ratings company has embedded a meter for digital content — in apps, players and on browsers — which can identify when a piece of content is running. The software meter picks up the audio watermarks that are already used for linear TV measurement to identify what that content is.

The new data collected will be rolled up into traditional TV ratings, existing in some data sets and not others at first. Initially, the service will launch in national numbers, then follow in local markets.

Turning machine-based information into actual people is another tricky part. Enter Facebook: Nielsen’s partnership with the social media giant will allow it to cross-match for demographic information as available.

“The biggest takeaway is this is very gradual,” Dounia Turrill, Nielsen senior vice president, Insights, told TheWrap following the panel. “The measurement is there, the implementation is there. But it really is a match of having the content and the clients fully implemented.”

Turrill added that it’s not really possible to say when we will see a significant change to the ratings numbers. It all depends on when individual Nielsen clients implement the program — which will not universally be on the same timetable for a variety of business reasons. Those that will benefit the most from the inclusion of mobile ratings will surely push to be among the first to adapt.

Nielsen will not release information on who is where on the implementation cycle without clients’ consent, so this could be a challenging fall and winter full of difficult comparisons between networks.

It will also be hard comparing the “new” numbers year-over-year, especially at first. Logically, with multi-platform numbers being rolled in and steady live TV consumption, one could expect this coming season’s TV ratings to be up from the one that just closed.

Beyond Nielsen’s initial preview period, its clients will be able to break out separate components to help show more accurate or specific numbers — touting growth or hiding the lack thereof. All this will make for an interesting rollout period, to say the least.

Finally, we still won’t be getting Netflix data, Nielsen told the frustrated entertainment journalists at the Beverly Hills Hotel. The streaming service has an option to opt-in to this measurement, but they have not.